Lafarge Canada’s Exshaw, Alberta, Plant Installs a Stack Silencer That Has Reduced Sound Levels and Created Community Good Will.

By Mark S. Kuhar

The installation included 13 silencer modules.

In January 2012, Lafarge North America finally said “no” to noise. At that time, they saw the completion of an intensive engineering project at its cement plant in Exshaw, Alberta, Canada, by Noise Solutions that resulted in a monumental reduction in sound levels.

Extensive research for the project began in 2009. This included exploring a combination of active noise control scenarios, as well as conducting monitoring surveys at four nearby residential located 240 to 500 meters from the plant.

The surveys revealed that the Exshaw facility was not in compliance with the Energy Resources Conservation Board’s (now the Alberta Energy Regulator) permissible nighttime sound levels of 48 dBA.

Making a RacketOne of the largest noise sources at the Lafarge Cement Plant was the K5 Gravel Bed Filter Stack, which is essentially a giant chimney. After more than a year of collecting data, modeling, engineering and manufacturing, Noise Solutions installed a massive 14,500-lb., 25-ft. tall stack silencer, designed to absorb noise-causing vibrations from one of the stacks.

Another significant noise source that needed to be addressed at the Lafarge site was the compressor room and vacuum system. Noise Solutions’ acoustically treated building ventilation inlet hoods were installed to attenuate the problem areas.

The installation, which also included 13 silencer modules on three large roof vents, was highlighted as a priority to Lafarge as a result of forum discussions with both plant employees and residents in the Exshaw community. These ongoing discussions eventually launched the Community Liaison Committee, which included eight members of the public and three of the plant’s senior management staff, to ensure better communication and enhance public perception of the plant’s operations within the community.

Getting an AwardShortly after the install of the Kiln 5 Stack Silencer and treatment to the hood vents, the town of Exshaw received Lafarge’s President’s Award in recognition for their outstanding leadership in Health and Safety.

Various seasonal conditions can affect the sound propagation efficiency between a facility and residents. Noise Control Regulation Directive 038, regulated by the former Alberta Energy and Utilities Board, allows for only 50 dBA during daytime hours and 40 dBA during nighttime hours.

Although a post-noise control site assessment has shown the treated noise sources have hit their noise reduction targets, work with Noise Solutions and Lafarge is ongoing at the Exshaw Plant, with more equipment to be built and installed, as well as a final noise impact assessment which will determine the final cumulative reduction overall for the site.

Information for this article courtesy of Noise Solutions.

What is a Noise Impact Assessment?

Established in 1997, Noise Solutions Inc. is a leading North American provider of engineered turnkey industrial noise control for energy, mining, power generation and aerospace. Its range of customizable equipment spans acoustic buildings, walls, enclosures and ventilation to a wide range of engine exhaust and cooler fan silencers.

Noise Solutions’ turnkey approach ensures customers deal with just one vendor for the entire project to ensure the most thorough service with unparalleled results – from the initial Noise Impact Assessment (NIA) right through to installation.

An NIA is an analytical examination of noise that emits from a facility, its significance relative to local regulatory limits, and what needs to be done to ensure the facility is in compliance.

An effective NIA will include the following steps:

Specialized technicians take specific and detailed measurements of various noise sources at a facility.

The sound power data received is derived from the existing onsite equipment manufacturer's data, sound pressure measurements, or theoretical calculations.

A report is produced that provides accurate noise levels that may be out of compliance and impacting a specific radius from the facility and nearby residents.

A detailed Source Order Ranking Table is provided identifying and prioritizing the loudest noise sources that require attenuation.

A Permissible Sound Level is established based on distance, dwelling unit density and proximity to transportation corridors along with engineered noise control recommendations.

Lafarge Exshaw Cement Plant History

In 1906, the Western Canadian Cement & Coal Co. opened what would become the most innovative and modern cement plant in the world. Nestled at the edge of the Rocky Mountains, the Exshaw plant site was chosen for the abundant quantity and quality of limestone, the availability of nearby power sources and its proximity to the CPR’s rail line.

The first people arrived in Exshaw in 1906; hired to build what would become the largest and most advanced industrial plant in the country. Three hundred young men, some with their wives and children, came from all over the world to find work in the rapidly expanding Canadian West. After construction was complete many of the workers moved on while others stayed, attracted by the potential of permanent work at the plant and a place to call home.

Rock blasting took place in the mountain above the plant and rocks were hand-loaded into small rail cars that travelled downhill to the crusher, the grinders and then into the kilns. Using six 80-ft. kilns the plant was able to produce 1,500-1,800 barrels of Portland cement per day.

In the early years, the half-a-million barrels of cement produced every year had a positive benefit to the local economy but also provided much of the necessary material needed to expand the roads, railways and industrial buildings used to develop Western Canada.

The plant was described as a technological wonder of its time, yet in 1908, slow markets, railway strikes and a flawed sales strategy caused the plant to close down. Although workers continued to quarry rock from the mountains above Exshaw it was not until new management and the 1909 amalgamation of 10 Canadian cement companies – to form the Canada Cement Co. – that the Exshaw plant began to operate again.

Many modernizations took place to keep the plant at the leading edge of technology and productivity:

The completion of the Seebe dam in 1911 provided inexpensive power to the plant and replaced the coal fired stream generator built in 1906.

In 1912, the six old kilns were replaced with three more efficient 150-ft. coal-fired kilns.

Post-war modernizations in the mid-1920s led to a temporary switch from blasting to hydraulic mining.

The 1940s saw the switch from a dry manufacturing process to the wet process.

In the early 1950s the plant introduced a new mountain top quarry and began using electric shovels, 30-ton trucks and a mobile rotary drill.

Exshaw was the first company plant to convert from coal to natural gas fired kilns in 1951.

In 1970 Canada Cement merged with Lafarge Canada to form Canada Cement Lafarge Ltd. This new company would become the largest supplier of cement in Canada and would be a major contributor to the development of Canada's two fastest growing cities, Calgary and Edmonton.

In the early 1970s a $30 million expansion and upgrade increased the plant capacity to 500,000 tons. Much of the old plant was demolished and the expansion required the demolition of much of Uptown Exshaw including the elementary school, protestant church and 47 homes.

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Cement Americas brings focus to issues affecting cementitious materials suppliers and is a bi-monthly magazine from the publishers of Rock Products. Despite the continued depressed condition of both the U.S. economy and construction activity, gains are being seen in cement consumption in the coming years. Read More